Reaction furnace for contacting a gas and fluidized solids



Oct. 20, 1953 F. L. sYMoNDs REACTION FURNACE FOR CONTACTING A GAS AND FLUIDIZED SOLIDS 3 Sheets-Sheet l Original Filed April 18, 1945 REACTION SE CT'/ ON .Z

Gas

SE CTON 2 F red L mono @y mw ,Y.;

mfom ey Oct. 20, 1.953 L SYMONDS 2,656,258

l REACTION FURNACE FOR CONTACTING A GAS AND FLUIDIZED SOLIDS Original Filed April 18, 1945 5 Sheets-Sheet 2 Secr/0N 90 y 94 95 sEcr/o/v secr/o 3 flue Gas 9 4l-r Invenon- Q Fred L. Symonds Oct. 20, 1953 F. l.. sYMoNDs REACTION FURNACE FOR CONTACTING A GAS AND FLUIDIZED SOLIDS 5 Sheets-Sheet 3 Original .Filed April 18, 1945 Patented Oct. 20, 1795.3

REACTION FURNACE Foa .ooNTAoTING li GAS AND FLUIDIZED somos Fred lL. Symonds; LbuisianayMq.; @signoff-f to- Standard Oil Company, Chcago,"Ill.-;-a -corporation of lIndiana Original ,application April :1&1'1945, Seii :N93 588,987, now Patent No. 2,490,986, -datedDe'-I cember 13, 1949. ,Dividedand ythis",application September' 20, 1949, Serial N1`116,6,73"

iclaims. (orgs-128s) 1A This inventionfrelats to an apparatus for conducting chemical 'reactionsin-the `gas gphase in the presence of `iinely ivided,4 uidized solids.' The solids may act as catalysts to accelerate a chemical reaction involving oneor more gases or vapors, or the solids may take part Ainthe reaction by supplying certain chemical substances thereto, or by abstracting chemical substances therefrom; The invention relates also to gas phase reactionsr conducted at pressures approximating atmospheric pressure,` and`4 still more particularly to aprce'ss in which powdered solids are contacted with gases in two or'mbre stages in series.

lThis application is adivision of my ka'pgplifcation Serial No. 588,987, iledApril'18,"1945, entitled Process of Producing Oxygenjancl now 'issued' as U. S. Patent 2,490,986; n L

One object of the inventionis "toprovidean' apparatus for conducting gas phase" chemical reactions in stages `wherein large volumes of uidized solids are maintained at elevatedtem'# perature in suspension in the gases' undergoing reaction. Other objects of the' inventionirfi'- clude the following: toprovide an apparatusv for transferring large volumes of 'uidiaed solids thru a series of separate reaction stages 'inv a multistage process with a* minimum ec'peifiditure of energy, minimum cost, and' substantially no pressure differential 'between the "stagesyto provide an apparatus for uniformly "contacting gases withA fluidized 'solids at relatively lowgas velocity and low pressure"differentials jbetwe'rr incoming and outgoingjgases; to'provi-de "an ap paratus for contacting gases with fluidized solids wherein the temperature Vof the contactingv mass' is controlled by radiation; and to provideja process of separating oxygenfrom air lay-contacting with fluidi'zed solids in'a'lowpres'sur system and to provide Aa-furnace for conducting gaseous reactions in "the presence 'off fluidied solids at high temperature in'which the fluid-ized solid vis retained` as a relatively A'shallowflayer; thus avoiding 'destruction of "they-apparatus by the movement ofV deep v`masses off luidizedfscilidls;v

The invention is -1 illustrated by drawings inE which:

paratus;

Figure 2 is an elevational'view of the same aphparatus;

Figure 3 vis Va sectional view ofthej'ap'p"aratus showingconstructio'ndetails' l l Figure '4` shows fthe ."floo'r vcen sij'lriici-zionidetail;

2 of wall cnstruction `'with provision for `'uidized solids transfer between stages;

Figure 6 is a section of a modied separator wall construction providing for transfer of iluidized solids;

Figure 7 is a flow diagram illustrating the use of the furnace, shown in plan, in a process of separating oxygen from air, with accessories shown in schematic'elevation;

Figure 8 is a plan view of an `alternativ/"e furnace-construction; l

Figure'9is a-modiied solids transfer lift.

Referring to Figure I1, showing the rectangular form of furnace, two -reaction sections are proin'betweem The wall is provided with ltransfer lifts ll and '|2--for*p`owdered solids. Aeration gas,1for exam-ple steam,v nitrogen, etc., is supplied to the lifts byv pipes l3and 14.

Referring ftoliigure, -the construction of the furnace oor is show-n in some detail. Above la' concrete slab l5 'theref'is Lsupported a Afalse floor' I6 or hearth constructed of open joint tile, brick, or preferably porous plate,` fritted porcelain :or silica wareyrefractoryat -the temperatures employellin ithe `"furn`acebutV suci'ently. porous 'to permit the upflow of gases therethrough. Be.- neath thefloor 16a-re gas-ducts il -to which are connected reaction-gas induction-lines I8 and i9"by"tuyres"20. Cooling may-be supplied -to the furnace byinjection-of lwater -thru a plurality of water^lines2i extending into the furnace. These may leffect cooling by indirect `conduction of heat as in the case offa water-coil heat 'exchanger. Where 4 a 'jlarge V-arnount `of Acooling is neled the'water `lines hi2 l- Amay be fperforated to supply ja Vwater spray to' f the yfurnace. It iis pre-` fe'rred to l"construct the-furnace -with horizontal roof'f22 to provide-'a Auniform distribution 4of radiant heat Afrorr'r'the'roof "of the furnace down-v Ward againstA the fluidized *solids `n'ioving'facross the furnace" floor.' y"Radiation betweenthebedE ojf "solids'and the roof mayLbefineither'direction from; hearth vto 'roof or' vice lversacdepending'fori whether the *solids arebeing heated or cooled.

The 'roof may be cooled by awater vspray!-wirfl-iinv the ,reaction'charnber for by other, meanswhere coolingis desired, oritfrnay be heated by adiarne or by' other'means' 'whenit' is desired-toradiantly heat' thesolid's"irthefbed0n-hearth 15.- Itis preferred that the roof` be substantially 'co-'egeA tensive with the hearth and it is 'importa-nttha-t the d ista'ncelbetweeri theA lroof-and the hearth-be relatively short, 'depending -upoiithe size/*of the than one-half the square root of the internal area of the roof and it is preferred that it be from one-quarter to one-tenth the square root of the internal roof area. The walls and roof of the furnace are constructed of suitable refractory material such as firebrick, magnesite brick, asbestos, etc.

The porous floor construction is shown inV greater detail in Figure 4 which illustrates a suit-` able arrangement for attaching and holding in place the porous tiles or plates I6. In this construction, bolt 23 imbedded in concrete base I5 serves to hold the porcelain washer 24 down on the tiles I6. Porcelain or tile support 25 is suitably made in the form of a 'cylinder on which the corners of four adjoining tiles are rested.

Connections for withdrawing gases from the furnace are indicated by headers 26 and 21 in Figure 2. In this gure, the header 26 is the gas outlet from reaction section I while 21 conducts the gas away from reaction section 2. Wall and roof supports are indicated at 28.

Referring again to Figure l, the fluidized solids maintained in turbulent motion by gases flowing upwardly therethrough from the porous floor of the furnace form a shallow pool, the depth of which is usually maintained at about 2 to 4 feet, more or less, depending on the reaction employed. As rapidly as solids are transferred thru the dividing wall between the reaction zones No. I and No. 2 in one direction, an equal amount of solids are transferred in the reverse direction following the arrows. The center bafe plate 253 serves to direct the flow of solids in a generally elliptical path to avoid short circuiting between the transfer lifts II and I2. It should be understood that the wall It may be in any suitable position dividing the furnace into sections of equal size. or unequal size as indicated, where the difference in reaction velocities requires a longer time of contact in one reaction zone than in the other. Reaction gas or vapor is supplied to reaction section 2 by line 30 with connections leading to the subfloor ducts beneath this section. For most operations, the level of the fluidized solids pool on each size of the wall I is about the same with the same pressure, usually atmospheric, in each section of the furnace.

A detail showing the construction of a suitable transfer lift II is shown in Figure wherein the dividing wall I0 may be of reinforced concrete construction, provided with a port 3l to which is connected lift tube 32. Tube 3.9. is of suitable refractory material such as porcelain or ceramic ware, or it may be of metal resistant to heat and corrosion, for example Chromel, calite or duriron. Aeration gas from supply line I3 is introduced thru a suitable nozzle 33 into the dependent open end of transfer lift 32 Bolts 34 employed in attaching the transfer lift to the dividing wall may be protected from heat and corrosion by asbestos cement covers 35.

It should be understood that the body of the furnace is preferablyconstructed of steel plates with gas-tight joints with provision for expansion and contraction of the refractory lining therein. The gas phase zones of the separate reaction sections are completely separated and gas is effectively prevented from passing from zone to zone by the iluidized solids transfer` lifts 32 which extend nearly to the floor of each section and the openings 3I in dividing wall I@ are thereby sealed by the pools of fluidized solids in their respective zones. Aeration supplied to the iluidized solidsin'lifts 3 2 reduces the density locally within the lift causing the solids to rise and iiow over thru the opening 3|. By directing the stream of solids horizontally or downwardly as indicated, there is a minimum of dispersion of the solids in the gas phase space of the section to which they are transferred. As indicated in Figure 5, the floor tiles 3S directly below the openings into the transfer lifts s2 may, if desired,`beimpervious to gases to prevent gases charged to the reaction zone from rising into the transfer lifts with the solids. The only gases transferred with the solids are therefore the aeration gas supplied thru nozzles 33 and the gas occluded in the solids from the reaction section.

If it is desired to remove occluded gases from the powdered solids passing from section to section, this may be accomplished by supplying solids to lifts I I and I2 by short downcomers into which the solids are subjected to inert stripping gas, for example steam. However, it is generally not necessary to resort to this expedient.

In Figure 6 is shown a simplified lift arrangement in which the dividing wall I9 between sections is provided with an opening or series of ports 31 at the bottom, and opposite the ports a weir 38 over which the iluidized solids are lifted by aeration gas injected thru line I3. Aeration line I3 may be a horizontal pipe line in the bottom of the lift space 39 included between the wall I3 and baffle 33 and aeration gas may be injected thru suitable nozzles fitted in line I3.

An alternative arrangement of furnace is shown in Figure 8 in which the plan of the furnace is circular instead of rectangular and the fluidized solids pursue a circular course from section to section. Four sections are illustrated as indicated on the drawing, the fluidized solids flowing under dividing walls 4B, fil, i2 and 53 as indicated by the arrows. Just as in the case of the rectangular furnace shown in Figure l, 'the reacting gases are injected thru the porous floor of each section and withdrawn from a higher point therein. The application of the furnace shown in Figure 8 to a process of abstracting oxygen from air will be described hereinafter.

There are many applications of my improved fluidized solid contacting furnace to industrial processes including such processes as the conversion of hydrocarbons, the cracking of hydrocarbon oils, the purification of gases, reduction of fluidized ores, manufacture of water gas, the prepartion of synthesis gas for the Fischer process by conversion of methane with metal oxides into carbon monoxide and hydrogen, etc. Following is a description of the application of this apparatus to the recovery of oxygen from air.

The process is especially applicable to making oxygen, particularly to the manufacture oi' industrial oxygen where high purity is not required and where the oxygen concentration in the product gas may Vary from about to 95 per cent. The use of my fluid flow furnace offers a method for making industrial oxygen more cheaply than has been possible heretofore. Thru the agenc of a metal oxide, or other agent existing in two states of oxidation cap'abie of acting as an Oxy.

gen carrier between two stages at different ternperatures, a regeneration stage and a decomposition stage, it is Vpossible to operate an oxygenV process with my furnace in a continuous unina.

terrupted manner with accurate control of temperature Yand without the necessity of indirectly applying heat to either the oxide regeneration stage or the oxide decomposition stage.

the gases.

aiutante jlrevius chemical processes for `the manufacture of oxygen, such as the Brin A`process employin g barium oxides and the du Motay process employing manganites, have been unable to 'compete with the liquid air process because of several inherent difficulties, one important difficulty being the intermittent operationwithlack of proper temperature control and heat balance between the various stages of the process. I have now discovered that -these difficulties encountered with the oxide -process can be overcome `when employing the oxide in the form of a luidized turbulent mass inthe furnace hereinabove `described and continuously `recycling the dense `iluidiied-mass as a pseudo liquid stream between two stages of oxidation. Bythis means I yhave found it possible to control the operation with far greater Aaccuracy `than has heretofore been possible, and as aresult the state of .oxidation `of the metal oxide is more uniformly regulated, giving greater production-of oxygen. I have also found that the decomposing stage, or lower stage vof oxidation, can be maintained at a higher temlsolids being circulated between the two sections thru dividing Wall 52 as indicated by the arrows. Steam for the transfer lifts is provided by lines 53 and 54. Regeneration air is supplied to section I by blower 55 and conduit 56, leading the air beneath the porous oor of the regeneration section. Spent regeneration gas consisting largely of nitrogen and some unused oxygen is conducted by line 51 to cyclone separatorV 58 wherein most of the entrained powdered solid oxygen carrier is recovered and returned tothe regenerator by line 5,9.

The remaining nitrogenous-gas from separator V58 is conducted by line 60 to Water scrubber 6l `where remaining oxygen carrier is recovered from A. second scrubbing stage is shown at 62, the gases being conducted ,from 6I to 62 byline 63. The spent gases are withdrawn by Vline 64 and exhauster 65. Water supplied by line 66 to scrubber 62 is conducted with any solids accumulated therein to the first scrubbing stage 6l, transfer line 61 being provided for the purpose. The slurry of recovered solids and Water isI returned to the regeneration zone of the oxygen furnace by line 68 and pump 69. In the regenerationzone 5l, the slurry is evaporated by the excess heat therein and simultaneously Aserves the useful purpose of reducing the temperature in the regeneration stage.

Regenerated oxygen carrier from 5I is heated to ay higher temperature in section 50 byany suitable means but preferably by the injection of combustible gas thru line 10 leading to the subl,floor spacebelowV section 50; the gas being evenly distributed throughout the mass of flowing,` turbulent iluidized solid oxygen carried bythe porous gas-permeable floor hereinbefore described. The amount of gas Vsupplied is just sufcient to consume aportion of the oxygen of the heat car- 111er and; gravide. as.. a result QI; the., combustion the amountV ofheat necessary to raise the tempera- Vture of the decomposition zonegto :the .desired idecomposition point. 'I-n atypical operation, the de.- lcomposition temperature may :be about 500 to 600 C. and (preferably about 55510 .C. Simultaneously the regeneration temperature may .be about 300 to 4509 C., vpreferably .about 40.0.;C.

Oxygen liberated bythe increased temperature ofthe decomposition zone 50 iswithdrawnfrcm the vapor spacethereof by iine.;1.l leading to cyclone separator 12 wherein entrained `solids are vremoved and returned byline 13 to the decomposition section. `The oxygen admixed with combustion products `from the heating gas supplied by line 10 is conducted by line 1A to scrubber 15, thence Y'by `line 16 to the `second scrubbing stage 11. Solids separated in the scrubbers .are

Aconveyed'fby water which is introduced thru line 18 to scrubber 11 thence byline 'i9 to scrubber 15 andthence by line 80 `backto regeneration zone 5l wherein the water is evaporated and the solids are returned to the furnace.

vSteam resulting fromv the Ycombustion in` section 50 is largely condensed in the scrubbers 15 and 1-1 and the remaining oxygen is led byline 8| to condenser tower 82 where it is further cooled, preferably by refrigerator coils, to removewthe remaining water and provide substantially dry oxygen to the outlet 83, condensed water :being discharged by line 84.

Where the heating gas supplied fby line 10 is a hydrocarbon gas or one-containing carbon compounds, e. g. water gas, the oxygen produced `will contain from 5 to 25` per cent of CO2. This-may be removed `by any suitable CO2-absorbingl system such as the alkali carbonate system, tr-iethanolamine, or other suitable process. For v.some purposes the oxygen may be employed without removal of CO2, for example in the smelting `of ores, refining of steel, and in the Fischer process for preparing synthesis gas. In the latter reaction, the oxygen is used to maintain the temperature 'of the gas maker in the water gas temperature range, e. g. 1700 to 2200 F., and anyCOz contained in the oxygen is converted to CO by the fuel employed be it coke, methane, or other suitable carbonaceous material.

Where a supply of hydrogen is available it 'may be employed as the heating gas in zone 50'thereby producing only Vwater on combustion in the decomposition zone, making it unnecessary to supply a carbon dioxide removal step in the process. A suitable source of hydrogen for the purposev is an adjacent electrolytic hydrogen-oxygen plant.

The oxygen produced in the electrolytic plant may be combined with the oxygen producedv'i'n the chemical process just described. Regardless of what heating gas is used, it is preferred to use a gas substantially free of nitrogen so that the oxygen produced in the process will notlbe contaminated with excessive amounts of nitrogen. Natural gas, reiinery gas, water gas or the tail gas from a syntholprocess may be employed. The gas may be preheated to. af high temperature. e. g. 5,00 to 1000 F., before introducing it into the decomposer, heat for the purpose being obtained largely by heat exchange with hot products withdrawn fromv the 'regenerator and/or the decomposer.

In the decomposer 50, the oxygen carrierlibcrates oxygen at the higher temperature ,prevailing therein and the liberation of oxygen is assisted by dilution with steam or other gases,l particularly the decomposition products, steam and CO2, resulting from the combustionof the heating gas introduced by line `10. y Y l rattacca In a typical petion' of my process; I may maintain the temperature of the regenerator at about 400 C., employing for the oxygen carr1er calcium manganite preferably deposited onasuitable carrier such as silica gel, clay, bauxite, diatomaceous earth, aluminum oxide, magnesia or an acid-treated clay such as Super Filtrol. The regenerated or reoxidized carrier is then conducted to the decomposer where it is heated to about 600 C. as hereinabove described, at which temperature oxygen is liberated and the calcium manganite is reduced to a lower state of oxidation, in which form it is recycled to the regenerator l2 wherein its temperature is again reduced to about 400 C., by water evaporation and cold regeneration air in which condition it is cap- :able of absorbing additional oxygen from the air 'introduced by blower 55. The temperature of the lhot oxygen carrier ilowing from 50 to 5l may also be reduced by passing it over indirect heat exchanger coils in the regenerator and the heat obtained in this way may be employed for regenerating steam or for other purposes.

Another oxygen carrier which may be used inthe process is calcium plumbate, preferably in admixture with manganese oxide and supported on a suitable, nely divided solid. Manganese oxides promoted with copper oxides may be employed at temperatures of 1000 to 1200 C. for the regeneration and disengaging stages, respectively. Catalysts may also be used. Certain other oxygen carriers may be employed, particularly the alkali metal manganites and plumbites, and barium oxide, if the operation is conducted with exclusion of C62 from the decomposer and regenerator. In order to operate satisfactorily with these oxygen carriers, it is necessary to carefully scrub the air employed in the regenerator to remove CO2, and it is not possible to employ carbonaceous gas for internally heating the decomposer. In that case, if hydrogen free of carbon compounds is not available for the purpose, it is necessary to supply heat to the decomposer indirectly. This can be accomplished by circulating the fiuidized solids in the decomposer thru a tubular furnace, not shown, indirectly heated to obtain the desired temperature.

In the operation of the furnace, the fiuidized solids oxygen carrier may suitably have a density of about 50 pounds per cubic foot when aerated in the furnace by an upflow gas stream moving with a vertical velocity of about four feet per second. In the transfer lifts from wall 52, the density of the fluidized solids oxygen carrier may suitably be reduced to about 20 to 30- pounds per cubic foot by additional aeration as indicated. Pressure in the furnace is suitably about 1 to 5 p. s. i. gage in each section.

The oxygen carrier, suitably calcium manganite in the form of a powder, may have a particle size Vcorresponding to 20 mesh and nner, ire. 50 to 200 mesh. Still finer material may be employed of the order of 300 to 400 mesh but if too fine, provision must be made for recovering the oxygen carrier from the gases in addition to simple settling or cyclone separation. The density of the oxygen carrier suspension when in operation will vary greatly with the nature thereof but it will usually be about 25 to 100 pounds per cubic foot depending on the specific material employed, its particle size, and the air velocity employed in the regenerator. The luidized suspension forms within the regenerator a pseudo liquid layer, the depth of whichis preferably -maintained at about 3 to 5 feet. Inasmuch as the regenerator normally Vmust be cooled, this may be accomplished by injecting regulated amounts of water by line 2l (Figures l and 3) the resulting steam passing off with the nitrogen thru line 26. In order to avoid dilution of the air in the uidized solids in the regenerator with the steam thus produced, I can inject the water into the gas space in the regenerator, thus cooling the bed of solids indirectly by radiation as indicated hereinabove. The steam resulting from the vaporization of cooling Water together with the residual nitrogen of the air charged to the regenerator is conducted from the regenerator by line 26 leading to a stack for producing natural draft to assist in operation of the regenerator.

Referring again to Figure 8 previously discussed, the circular furnace shown in sectional plan View is provided with four sections instead of two as in the case of the furnace described in Figure 1. In section No. l, the regenerating Zone, the oxygen carrier is oxidized to a higher state of oxidation by air injected below the porous floor of the furnace, air being supplied by c-lovver thru duct 86 and denuded air consisting largely of nitrogen and about 2 to l0 per cent of oxygen is discharged to the flue by line 81 connected to the gas space in section No. l.

From section No. i the uidized solids flow thru dividing wall 40 into section No. 2 in which the temperature is raised by the introduction of a fuel gas, e. g. methane, by line S8 connecting to the suboor space below the fluidized solids bed. At the higher temperature, e. g. 550 C., the oxygen is disengaged and discharged by line 89. Sufficient lime or other suitable oxide is employed with the oxygen carrier in iiuidized iinely divided form to absorb in section 2 carbon dioxide produced in the combustion of the heating gas, calcium carbonate being formed by the carbonation of the lime. The oxygen discharged thru line 8S is accordingly substantially free of carbon dioxide and for most processes will require no further decarbonation.

The fluidized solid oxygen carrier and calcium carbonate are now conducted to section No. 3 wherein the temperature is still further increased, e. g. to 500 to 1000 C., as a result of the combustion of additional fuel gas supplied by line interacting with air supplied by line 9i. At the higher temperature obtained in Section No. 3, the lime is calcined, regenerating calcium oxide and discharging CO2 to the flue by line 92. Combustion gas and air may be mixed in a suitable burner before injecting into the subfloor space in section No. 3, the heated combustion products passing upwardly thru the layer of uidized solids and the flue gas being discarded from the gas space in section No. 3 by line 92.

The calcined mixture of oxygen carrier and lime is next cooled in section No. 4 by a water spray or by indirect cooling, the temperature being again returned' to 300 or 400 C. before returning the oxygen carrier and lime thru dividing wall 43 into section No. l for recharging with oxygen.

VThe fluidized solids transfer lift zone in Figure 9 is a modification of that shown in Figure 6 previously described. Its operation differs in that the dividing wall 93 is located on the outflow side of the baiile 96, whereas in `Figure 6 the dividing wall lil is on the inlet side of the space dened between therwall I0 and baille 38. Aeration gas supplied by perforated pipe 95 serves to reduce the density of the fluidized solids in the space between the baille 94 and floating baffle 96, forming a chimney within which the fluidized solids rise to an elevation above the level of the fluidized bed 91. Aeration gas escapes from the solids at the surface 98 allowing the iiuidized solids which spill over baffle 94 to flow by gravity under wall 93 into the adjacent chamber 99. With this form of transfer lift, there is less danger of escape of gas from the gas phase of one section to the gas phase of the adjacent section under dividing wall 93 for the reason that the fluidized solids bed level is higher at the dividing wall than the average level of the fluidized bed in the adjoining chambers.

As hereinabove indicated, oxygen made by my process is particularly advantageous for use in the Fischer process of hydrocarbon synthesis. Carbon dioxide which it contains as a result of the combustion reaction in the metal oxide decomposition stage can be reduced to carbon monoxide at water gas temperatures in the gas preparation step for Fischer synthesis. In carrying out this procedure, the oxygen from the decomposition zone containing from 10 to 50 per cent of CO2 and a small amount of nitrogen, e. g. to 15 per cent, is conducted preferably while hot to the gas preparation reaction chamber which is suitably maintained at a temperature of about 800 to 1100 C; Additional fuel is supplied to the gas preparation chamber and for this purpose solid liquid or gaseous fuels may be employed, such as coke, residual oils, fuel oils, natural gas, etc. It is preferred to employ hydrocarbon gases, particularly methane. In the preparation step, the methane is converted to carbon monoxide and hydrogen by the action of the oxidizing gas from the oxygen generator. Part of the hydrogen serves to reduce the carbon dioxide to carbon monoxide, an endothermic reaction absorbing part of the heat generated by the action of the oxygen on the methane, thus serving to balance the reaction thermally. The temperature is controlled by regulating the proportion of methane to oxygen employed in the gas preparation converter. Additional control may be obtained by segregating a portion of the oxygen-CO2 product from the oxygen generator, extracting CO2 from it, e. g. by solution in water under pressure or by selective solvents such as triethanolamine, sodium carbonate, etc., and then charging it to the gas preparation reactor, preferably after reheating in a suitable heat exchanger. Superheated steam may also be supplied to the gas preparation reactor to assist in controlling the composition of the products, particularly the ratio of hydrogen to carbon monoxide produced. For some reactions it is desirable to make a synthesis gas having a ratio of hydrogen to carbon monoxide of 2:1 whereas in other operations lower hydrogen ratios are desirable, e. g. 1.5:1. .A higher ratio of hydrogen to carbon monoxide is usually desirable where the gas is employed in the synthesis of methanol.. Where the gas is desired for the meth@ anol synthesis rather than hydrocarbon synthesis as in the Fischer process, the gas preparation converter may be operated under conditions to allow carbon dioxide to remain unreduced in the product gases and the carbon dioxide can be converted to methanol in the methanol synthesis step.

Although I have described the application of my invention to certain specific processes, it should be understood that this is by way of illustration and is not a limitation of the scope ofV 10 the invention. In addition to the application of the invention to the process of oxygen recovery, it may also be applied to conversion of hydrocarbon gases, cracking of hydrocarbon oils, purification of gases, for example desulfurization and decarbonation, and in general any process in which a gas is contacted with a uidized solid contact agent, catalyst or chemical reagent. In my copending application, Serial No. 613,792, filed August 31, 1945, entitled Natural Gas Conversion to Hydrogen and Carbon Monoxide, and issued as U. S. Patent 2,631,094, I have shown a method of making feed gas for the Fischer process, using fluidized solids as oxygen carriers. The scope of the invention is described by the following claims.

I claim:

l. An apparatus for contacting finely divided solids and gases, said apparatus comprising a furnace chamber, a gas permeable hearth within said chamber, a gas-induction space beneath said hearth, a refractory roof within said chamber over said hearth, a gas-contacting space above said hearth and below said roof within said chamber, an upstanding wall means extending between said roof and said hearth dividing said furnace chamber into at least two furnace sections above said hearth and at least two gas-induction spaces below said hearth, port means comprising at least one port in one portion of said wall means adapted to discharge flowing solids from a rst one of said furnace sections into a second one of said furnace sections above said hearth and additional ports in another portion of said wall means adapted to discharge flowing solids from said second furnace section into said first furnace section, thereby providing series ow of solids through said sections, said port means in said wall portions comprising a plurality of inverted J tubes having the stems depending into the respective discharging section, separate duct means for supplying separate gas streams to said gas-induction spaces beneath said hearth, and separate conduit means for withdrawing gases separately from the said furnace sections above said hearth.

2. The apparatus of claim 1 wherein the refractory roof of said furnace chamber above said hearth is in radiant heat relation thereto and the distance between the roof and hearth is less than one-half the square root of the internal area of the roof.

3. The apparatus of claim 1 wherein the furnace chamber is rectangular in shape, the said wall divides the furnace chamber into a minor References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 2,371,619 Hartley Mar. 20, 1945 2,385,446 Jewell et al Sept. 25, 1945 2,404,944 Brassert July 30, 1946 2,464,812 Johnson Mar. 22, 1949 2,468,508 Munday Apr. 26, 1949 2,477,042 Burnside July 26, 1949 2,477,751 Johnson Aug. 2, 1949 2,539,263,v

Munday Jan. 23, 

1. AN APPARATUS FOR CONTACTING FINELY DIVIDED SOLID AND GASES, SAID APPARATUS COMPRISING A FURNACE CHAMBER, A GAS PERMEABLE HEARTH WITHIN SAID CHAMBER, A GAS-INDUCTION SPACE BENEATH SAID HEARTH, A REFRACTORY ROOF WITHIN SAID CHAMBER OVER SAID HEARTH, A GAS-CONTACTING SPACE ABOVE SAID HEARTH AND BELOW SAID ROOF WITHIN SAID CHAMBER, AN UPSTANDING WALL MEANS EXTENDING BETWEEN SAID ROOF AND SAID HEARTH DIVIDING SAID FURNACE CHAMBER INTO AT LEAST TWO FURNACE SECTIONS ABOVE SAID HEARTH AND AT LEAST TWO GAS-INDUCTION SPACES BELOW SAID HEARTH, PORT MEANS COMPRISING AT LEAST ONE PORT IN ONE PORTION OF SAID WALL MEANS ADAPTED TO DISCHARGE GLOWING SOLIDS FROM A FIRST ONE OF SAID FURNACE SECTIONS INTO A SECOND ONE OF SAID FURNACE SECTIONS ABOVE SAID HEARTH AND ADDITIONAL PORTS IN ANOTHER PORTION OF SAID WALL MEANS ADAPTED TO DISCHARGE FLOWING SOLIDS FROM SAID SECOND FURNACE SECTION INTO SAID FIRST FURNACE SECTION, THEREBY PROVIDING SERIES FLOW OF SOLIDS THROUGH SAID SECTIONS, SAID PORT MEANS IN SAID WALL PORTIONS COMPRISING A PLURALITY OF INVERTED J TUBES HAVING THE STEMS DEPENDING INTO THE RESPECTIVE DISCHARGING SECTION, SEPARATE DUCT MEANS FOR SUPPLYING SEPARATE GAS STREAMS TO SAID GAS-INDUCTION SPACES BENEATH SAID HEARTH, AND SEPARATE CONDUIT MEANS FOR WITHDRAWING GASES SEPARATELY FROM THE SAID FURNACE SECTIONS ABOVE SAID HEARTH. 